Traditionally, the primary function of envelopes has been to identify the intended recipient and protect contents during transport, including transport via an intermediate carrier delivery system such as the United States Postal Service. In the latter regard, it is an inherent requirement that envelopes be capable of withstanding the rigorous handling normally associated with transport via a carrier delivery system.
More recently, with the increased use of direct mail advertising, envelope designs are also being employed to differentiate and thereby attract a recipient's attention. For example, the exterior of many envelopes now include unique colors and patterns. Further, the exterior of many envelopes now prompt recipients to open the same by creating a special interest or curiosity as to the contents. For example, a printed message on the envelope can partially describe the contents of the envelope in an enticing way, or an opening on the envelope can be used to allow the recipient to preview a select portion of the contents of the envelope.
Similarly, for envelopes used with special occasion cards, invitation, or the like, there is an increasing use of external features to impart interest or frivolity. For example, the exterior of such envelopes may include a special message applicable to the intended recipient and suggesting the nature of the contents, thereby enhancing the anticipation and enjoyment of the recipient.